1. Field of the Invention
The invention relates to a print head assembly for non-impact printing and is applicable to any non-impact print head in which the print elements of the head and conductors for supplying signals to the elements are made by printed circuit techniques. Thus, although specifically relating to print heads designed for use with so-called resistive ribbons in order to print on plain paper, the invention is equally applicable to other heads such as, for example, thermal print heads designed to generate heat directly in order to print on heat sensitive paper, or even electro-erosion heads designed to print on electro-sensitive paper; provided that these heads are constructed using printed circuit techniques.
2. Description of the Prior Art
In each case, the print head is provided as a plurality of closely spaced electrodes extending across a supporting substrate and terminating in a line adjacent one edge of the substrate to define a line of print elements. In use, the print head is mounted adjacent a print receiving medium with the line of print elements disposed at right-angles to the intended print row direction. A print mechanism typically moves the print head across the medium in the row direction with circuits selectively energizing the individual electrodes to cause printing along the row in known manner.
As part of a development effort to produce a low cost in-contact printer with consistently high print quality, it has been found advantageous to construct the print head assembly so that a worn print head may be removed easily by an operator and replaced by a new one. One advantage which accrues from the decision to make the print heads interchangeable is that the importance of developing a long life head is reduced with a consequent reduction in cost. Simple replacement of a print head as necessary also makes servicing easier and cheaper.
Furthermore servicing by the customer himself becomes more practicable. It is essential for the commercial success of the printer that the method for removal and installation of the print heads is substantially fool-proof and is simple and quick to perform.